Carburetor



Sept. 7, 1943.

' E. o. WIRTH CABBURETCR fi ed July 26, ,1940

Q 'INVENTOR EM. 0. W/RTH 922 Patented Sept. 7, i943 v UNITED STATES PATENT OFFICE cmurmrcn Emil o. Wirth, South Bend, na, assignor to Bendix Aviation Corporation, South Bend,

Ind., a corporation of Delaware Application July 26, 1940, Serial No. 347,633

' 6 Claims. (creel-16).

This invention-relates generally to carburetors and particularly to fuel discharge iets for multiple Venturi carburetors.

In carburetor construction utilizing an inclined tubular type of main fuel nozzle from which the fuel is discharged angularly into the primary Venturi, it is found that the resulting fuel distribution in the induction passage is not uniform. At low engine speeds fuel is discharged from the nozzle with little force so that it tends to follow the nozzle side o'f the induction passage. The fuel mixture therefore tends to be richer along this side of the passage than along the other, resulting in non-symmetrical fuel delivery to the intake manifold and uneven distribution by the latter to the-engine cylinders so that some cylinders receive a richer mixture'than others. Such uneven distribution to the cylinders results in increased fuel consumption and decreased power, as is generally known, and may in extreme cases cause the engine to run unevenly.

On the other hand, during relatively-high engine speeds, the fuel is drawn from the nozzle with considerable force and tandem flow along the side of the passage opposite the nozle. Un-

der these circumstances uneven distribution of the fuel mixture to the enginelalso occurs and irregular engine operation results. It is an important object of the present invention to provide a multiple Venturi carburetor in which the fuel is uniformly distributed across the carburetor induction passage at all engine speeds.

Another object of the invention is to provide a device of this character that has a fuel discharge passage extendinglongitudinally of the carburetor induction passage, the fuel passage flared outwardly at its discharge end.,

Still another object of the invention is to provide a device of this character wherein fuel is discharged in the direction of air movement in the induction passage.

The invention is further characterized by elongation of the fuel discharge opening extending diametrically in the induction passage; and the turi embodying the invention and taken on line embodiment of the invention, a downdraft carburetor having an air horn section It, a main body section l2, and a throttle body section I! having a flange It for attaching the carburetor to the intake manifold of the engine. The carburetor induction passage comprises an air inlet l8 controlled by an offset choke valve 20 mount-' ed on a shaft 22 and controlled by any suitable manual or automatic means, a primary venturi 24, a secondary venturi 26, a mixing chamber 28, and a mixture outlet 30. A throttle valve 82 mounted on throttle shaft 31 controls the mixture outlet in the known manner.

A fuel chamber 35 in the main body section has a float 38 mounted by any well known means (not shown) for controlling the level L-L 01' fuel in the chamber. Idling jet 40 of known construction is supplied with idling fuel from chamber 36 by means of communicating passages 42, M and 48, the latter having the usual idling tube 58 secured therein. The lower end of passage 48 communicates with an acceleration well it I formed by an enlargement of the bore in which xtension of the opening entirely across the air Figure l is a vertical section through a carburetor embo v .i. the invention;

Figure 2 is a bottom pian view of the small venmain fuel jet 52, of known construction, is received. The Jet 52 is secured in the bore by a plug lit screwed into a boss formed integral with a wall of the main body section it. The plug 54 is provided with a metering, orifice 56 sup- ,plied with fuel from chamber 86 through passage 5B and air is bled into the jet 52 from an an air bleed B0, in the known manner.'

The main fuel discharge nozzle 62 is of the bar type and is formed integral'with the small or primary venturi 24 in the entrance portion thereof, the small venturi being supported in the induction passage by diametrically extending. V

integral webs M. The nozzle 62 has a downwardly opening the] discharge passage 66 gradually fiaring convexly outwardly toward the discharge opening 68, the latterbeing at the downstream end of the nozzle so that fuelis discharged in the direction of movement of the air current.

The opening til is elongated-transversely of the nozzle 1 d extends entirely across the Venturi tube at =11 e place ofdischarge. The upper end of the passage 86 receives fuel from the main fuel Jet 52 through a duct it.

Invoperation, the nozzle 62 directs and discharges fuel in the same direction as the air stream through the venturi in which said nozzle is disposed. The fuel discharge passage extends axially inthe primary venturi thereby directing fuel in a uniform manner relative to the crosssectional area of the venturi. By flaring the discharge end of the passage diametrically to the side walls of the venturi, a uniform discharge of fuel is provided diametrically across the full width of the venturi at the place of discharge, and one side of the induction passage receives substantially the same amount of fuel as the other regardless of engine speed.

It is thought that the invention and many of its attendant advantages will be understood from the foregoing description, and it will be apparent that various changes may be made in the form, construction and arrangement of the parts without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the form hereinbefore described being merely a preferred embodiment thereof. Thus, the invention may be applied, not only to the double Venturi type of carburetor shown in the drawing, but also to triple or other multiple venturis, either of the updraft or downdraft type.

I claim:

1. In a, carburetor, an induction passage including a large and a small venturi, and a relatively narrow bar nozzle integral with the small venturi and extending transversely within same, said nozzle having a fuel passage including a tubular portion coaxial with said small venturi and a narrow convexly flared portion terminating in an elongated discharge slot for discharging 'fuel in the direction of' air flow in the induction passage.

2.' In a carburetor having an induction passage, a bar nozzle in said induction passage having a fuel discharge duct for discharging fuel into said induction passage, said duct including a tubular portion and a slotted discharge opening substantially rectangular in outline, said tubular portion radually fla utwa y to the ends of the discharge opening, and said flared portion being relatively narrow in width.

3. In a carburetor having aninduction passage, a bar nozzle in said passage having a fuel discharge passage, said fuel discharge passage terminating at one end in an opening substantially rectangular in outline from which fuel is discharged into the induction passage, said fuel discharge passage being relatively narrow and curving convexly inwardly of the ends of said opening to an inlet portion.

4. In a downdraft carburetor having an induc- 5 tion passage, a large and a small venturi included in said induction passage, a narrow bar nozzle in the small venturi and integral therewith, said nozzle being substantially rectangular in cross section and having a convexly flared fuel discharge passage, the fuel discharge passage having a slot-like opening discharging down stream relative to the air current through the small venturi.

5. In a downdraft carburetor, an induction passage having a plurality of venturis therein, a

downwardly discharging bar nozzle in one of said venturis, said nozzle having a narrow outwardly flared fuel passage terminating in.a discharge opening extending across the venturi in which the nozzle is located, and means for bleeding air to said fuel passage anterior to the discharge opening. 1

6. In a downdraft carburetor, an induction passage, and a relatively narrow bar nozzle therein having a fuel discharge passage including a 5 tubular portion extending longitudinally of the induction passage and a narrow portion gradually flaring from the lower end of said tubular portion to a discharge opening substantially rectangular in outline and of substantially the same 40 width as the diameter of the tubular portion,

said discharge opening extending diametrically of the induction passage. EMIL O. WIRTH. 

